This disclosure relates to semi-crystalline polymers and to articles manufactured therefrom.
Semi-crystalline thermoplastic polymers having high elastic modulus and tensile strength are generally produced by ultradrawing the polymer under uniaxial or biaxial stress. When the stress is applied to molten semi-crystalline thermoplastic polymers under specific conditions, the polymer undergoes flow induced crystallization, producing high crystalline polymer articles with high mechanical modulus. The use of directed stress however produces highly anisotropic properties, where the properties in stressed direction are very different from the properties in other directions, with 1000 to 3000% greater mechanical modulus in the draw direction, relative to the mechanical modulus perpendicular to the draw direction. In addition, articles prepared by flow induced crystallization that display such properties are generally in film or fiber form. Improved properties in the stressed direction over other directions are due primarily to high crystal volume fraction and high crystalline orientation in the direction of stress.
It is desirable to use flow induced crystallization to produce thermoplastic polymers with high crystallinity, where the high elastic modulus and strength properties are isotropic and not restricted to particular directions or to particular portions of the polymer, or mildly anisotropic, with up to 1000% increase in mechanical modulus in the draw direction, relative to the mechanical modulus perpendicular to the draw direction. It is also desirable to use flow induced crystallization to produce highly crystalline bulk thermoplastic polymer articles other than films and fibers, such as plates and rods.